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<div><a href="../index.html">Home</a> &gt;  <a href="index.html">v_mfiles</a> &gt; v_horizdiff.m</div>

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<h1>v_horizdiff
</h1>

<h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>V_HORIZDIFF - Estimates the horizontal difference between two functions of x</strong></div>

<h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>function [z,zm]=v_horizdiff(y,v,x,u,q) </strong></div>

<h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre class="comment">V_HORIZDIFF - Estimates the horizontal difference between two functions of x

 Usage: z=horizdiff(y,v,x); % Approximately: y(x) = v(x+z)

  Inputs: y(n,m) each column is a function of x
          v(k,1) reference function of u
          x(n,1) x values [default: x'=1:n]
          u(k,1) x values for v [default: v=x]
          q      interpolation mode
                    'l' linear [default]
                    'p' pchip (n&gt;=2)
                    's' spline (n&gt;=4)

 Outputs: z(n,m)   horizontal difference between v and y
          zm(1,m)  MMSE horizontal difference that minimizes sum((y(x)-v(x+z)).^2)</pre></div>

<!-- crossreference -->
<h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
This function calls:
<ul style="list-style-image:url(../matlabicon.gif)">
</ul>
This function is called by:
<ul style="list-style-image:url(../matlabicon.gif)">
</ul>
<!-- crossreference -->


<h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre>0001 <a name="_sub0" href="#_subfunctions" class="code">function [z,zm]=v_horizdiff(y,v,x,u,q)</a>
0002 <span class="comment">%V_HORIZDIFF - Estimates the horizontal difference between two functions of x</span>
0003 <span class="comment">%</span>
0004 <span class="comment">% Usage: z=horizdiff(y,v,x); % Approximately: y(x) = v(x+z)</span>
0005 <span class="comment">%</span>
0006 <span class="comment">%  Inputs: y(n,m) each column is a function of x</span>
0007 <span class="comment">%          v(k,1) reference function of u</span>
0008 <span class="comment">%          x(n,1) x values [default: x'=1:n]</span>
0009 <span class="comment">%          u(k,1) x values for v [default: v=x]</span>
0010 <span class="comment">%          q      interpolation mode</span>
0011 <span class="comment">%                    'l' linear [default]</span>
0012 <span class="comment">%                    'p' pchip (n&gt;=2)</span>
0013 <span class="comment">%                    's' spline (n&gt;=4)</span>
0014 <span class="comment">%</span>
0015 <span class="comment">% Outputs: z(n,m)   horizontal difference between v and y</span>
0016 <span class="comment">%          zm(1,m)  MMSE horizontal difference that minimizes sum((y(x)-v(x+z)).^2)</span>
0017 <span class="comment">%</span>
0018 
0019 <span class="comment">%       Copyright (C) Mike Brookes 2012</span>
0020 <span class="comment">%      Version: $Id: v_axisenlarge.m 10865 2018-09-21 17:22:45Z dmb $</span>
0021 <span class="comment">%</span>
0022 <span class="comment">%   VOICEBOX is a MATLAB toolbox for speech processing.</span>
0023 <span class="comment">%   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html</span>
0024 <span class="comment">%</span>
0025 <span class="comment">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span>
0026 <span class="comment">%   This program is free software; you can redistribute it and/or modify</span>
0027 <span class="comment">%   it under the terms of the GNU General Public License as published by</span>
0028 <span class="comment">%   the Free Software Foundation; either version 2 of the License, or</span>
0029 <span class="comment">%   (at your option) any later version.</span>
0030 <span class="comment">%</span>
0031 <span class="comment">%   This program is distributed in the hope that it will be useful,</span>
0032 <span class="comment">%   but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
0033 <span class="comment">%   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the</span>
0034 <span class="comment">%   GNU General Public License for more details.</span>
0035 <span class="comment">%</span>
0036 <span class="comment">%   You can obtain a copy of the GNU General Public License from</span>
0037 <span class="comment">%   http://www.gnu.org/copyleft/gpl.html or by writing to</span>
0038 <span class="comment">%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.</span>
0039 <span class="comment">%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%</span>
0040 <span class="comment">%</span>
0041 <span class="comment">%</span>
0042 <span class="comment">% choose interpolation method</span>
0043 <span class="comment">%</span>
0044 [n,m]=size(y);
0045 <span class="keyword">if</span> nargin&lt;5 || isempty(m)
0046     q=<span class="string">''</span>;
0047 <span class="keyword">end</span>
0048 <span class="keyword">if</span> n&gt;=4 &amp;&amp; any(q==<span class="string">'s'</span>)
0049     im=<span class="string">'spline'</span>;
0050 <span class="keyword">elseif</span> n&gt;=2 &amp;&amp; (any(q==<span class="string">'s'</span>) || any(q==<span class="string">'p'</span>))
0051     im=<span class="string">'pchip'</span>;
0052 <span class="keyword">else</span>
0053     im=<span class="string">'linear'</span>;
0054 <span class="keyword">end</span>
0055 <span class="keyword">if</span> nargin&lt;3 || isempty(x)
0056     x=(1:n)';
0057 <span class="keyword">end</span>
0058 <span class="keyword">if</span> nargin&lt;4 || isempty(u)
0059     u=x;
0060 <span class="keyword">end</span>
0061 <span class="comment">%</span>
0062 <span class="comment">% Interpolate inverse function, u(v)</span>
0063 <span class="comment">%</span>
0064 z=interp1(v,u,y,im,<span class="string">'extrap'</span>)-repmat(x,1,m);
0065 <span class="keyword">if</span> nargout&gt;1
0066     zm=zeros(1,m);
0067     ff=@(zm,c)sum((c-interp1(u,v,x+zm,im,<span class="string">'extrap'</span>)).^2);
0068     <span class="keyword">for</span> i=1:m
0069         zm(i)=fminbnd(@(zm) ff(zm,y(:,i)),u(1)-x(end),u(end)-x(1));
0070     <span class="keyword">end</span>
0071 <span class="keyword">end</span>
0072 <span class="keyword">if</span> ~nargout
0073     subplot(212);
0074     plot(x,z);
0075     xlabel(<span class="string">'x'</span>);
0076     ylabel(<span class="string">'x shift'</span>);
0077     <span class="keyword">if</span> all(abs(z-z(1))&lt;=z(1)*1e-4)
0078         set(gca,<span class="string">'ylim'</span>,2*[min(z(1),0) max(z(1),0)]);
0079     <span class="keyword">end</span>
0080     subplot(211);
0081     plot(x,y);
0082     hold on
0083     plot(u,v,<span class="string">':k'</span>);
0084     hold off
0085     ylabel(<span class="string">'y and v'</span>);
0086 <span class="keyword">end</span></pre></div>
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